The present invention pertains to a plug-in circuit board for insertion into and withdrawal from a rack which has at least one front profile rail, the circuit board including a front plate and a pivotably-mounted, lever-latch handle with a gripping bar.
In order to insert a plug-in circuit board into a rack, or in order to pull it out again from the rack, push in and pull out devices have long been known in the art. In the past various types of lever-latch handles and levers have been developed for insertion and removal of the plug-in circuit board. The forces to be applied for insertion and removal depend in large measure on the number of poles and plug connectors located on the back side of the plug-in circuit board and that are connected to corresponding plug-in connectors on the so called backplane of the rack. These multi-way connectors have, in recent times, been provided with an increased number of pins, so that the forces to be applied for insertion and removal are also increasing. Accordingly, the lever and lever-latch handle has to be made increasingly sturdier. Due to the use of multi-pin plug-in connectors on the back side of plug-in circuit boards, elastic deformations of individual components of the overall plug-in circuit board will occur due to the large plug-in forces.
During the process of placing a plug-in circuit board into a rack, the lever path of the lever-latch handle is limited either by a front plate located in the front region of the plug-in circuit board, or by a separate stop. The limitation of the lever path of the lever-latch handle keeps the push-in operation from being entirely completed, since the large plug-in forces at the multiple pin plug connectors cannot be overcome. Consequently, an elastic spring back of the plug-in circuit board or a reverse deformation of the plug-in circuit board will occur. The plug-in circuit board will then not fit flush with the rack and a visible gap will be formed in the front region between the plug-in circuit board and the rack, which has an adverse impact on the shielding effect of the rack.
Modern subassemblies are pushed into the rack in the inactive state. Once they are fully inserted, they will be activated because a switch located on the plug-in circuit board is operated. If the plug-in circuit board is not fully inserted into the rack, or if a spring-back of the plug-in circuit board occurs, then the switch will not be satisfactorily operated. The plug-in circuit board either will not be switched to become active, or a chattering of the switch may occur.
Also, in an attempt to pivot the lever-latch handle past its stop, damage to the lever, to the front plate and to the stop may occur due to the overtravel, or deformations of individual components may result.
In the telecommunications industry, plug-in circuit boards with a standardized lever are known that are designated as so called ATCA handles. These plug-in circuit boards have an additional magnetic stop, for example, in their front region, against which the metal lever-latch handle rests when the plug-in circuit board is in the pushed in state and by which it is held in its intended position. If the plug-in circuit board is not pushed in entirely due to the large plug in forces at the back side plug-in connector, then there will also be a spring-back or a reverse deformation of the plug-in circuit board as well. The lever will then not be held in its end position by the magnet. Any pivoting past the normal end position will also lead to damage to the stop and/or to the plug-in circuit board.
Therefore, it is the objective of the present invention to overcome the disadvantages of the prior art and to propose a lever-latch handle that will allow a certain amount of overtravel in order to avoid the spring-back of the entire assembly and damage to the plug-in circuit board or to the lever.